(1) Field of the Invention:
This invention relates to a passive seat belt system for a vehicle, which serves to restrain and protect an occupant in the event of a vehicular emergency such as a collision. Specifically, this invention is concerned with a device for permitting an upward or downward adjustment of an anchor base to choose a suitable point for a shoulder webbing in a motor-driven two-point passive seat belt system for an automotive vehicle.
(2) Description of the Related Art:
As illustrated in FIG. 11, a passive seat belt system for an automotive vehicle automatically restrains and protects an occupant by driving a slider 2, to which an occupant-restraining webbing 1 is fastened, with a motor 3 to cause the slider 3 to move between an occupant-releasing position and an occupant-restraining position along a slide rail 4 provided in the interior of the automotive vehicle.
The slider 2 is designed to engage an anchor base 5 at the occupant-restraining position. The anchor base 5 is located on a center pillar 7 of a vehicle body and serves to transmit a load, which is applied upon collision, to a body of the automotive vehicle, thereby supporting the occupant.
In such a passive seat belt system, it is necessary to adjust the height of the slider 2 approximately to the position of the outboard shoulder of the occupant at the occupant-restraining position. If the slider 2 is lower than his outboard shoulder, the webbing 1 extends over his outboard arm. On the other hand, if it is higher than his outboard shoulder, the webbing 1 extends over his face. It will therefore be impossible to protect the occupant safely in the event of an emergency.
To permit adjustment of the slider-fixing point to a suitable height, an anchor base adjusting mechanism is used to move and position the anchor base 5 as shown in FIG. 12. The anchor base adjusting mechanism is used in the following manner. The slider 2 is first of all moved to the occupant-releasing position. The anchor base 5 is then shifted either upward or downward along the slide rail 4 mounted on the center pillar 7 of the vehicle body, whereby the position of the anchor base 5 is adjusted. In the center pillar 7, there are formed positioning holes 8 and a load-receiving slot 9 as depicted in FIG. 13. By choosing one of the positioning holes 8, the height of slider 2, namely, the position of the upper end of the shoulder webbing 1 is adjusted.
When viewed from the front of the automotive vehicle by way of example, the center pillar 7 of the vehicle body does not extend linearly in the vertical direction but extends vertically in a pattern curved outboard with a large radius of curvature. It is therefore necessary to bring the configurations of members, such as the slide rail 4 attached to the center pillar 7 and the anchor base 5 provided along the length of the slide rail 4, into conformity with the curved shape of the vehicle body. If the anchor base 5 is linear in spite of the curved configuration of the slide rail 4, the anchor base 5 cannot be shifted or even if its shifting is feasible, the shifting is by no means smooth.
The anchor base 5 has heretofore been fabricated by bending an iron plate into conformity with the curved configuration of the center pillar 7 of the vehicle body. However, such bending of an iron plate is very difficult and is accompanied by a drawback that the resulting anchor base is costly.